Rocket ignitor construction



Oct. 2, 1962 F. w. BRUNKHARDT 3,056,257

ROCKET IGNITOR CONSTRUCTION Filed June 25, 1959 INVENTOR FREDERZCK W. BRLJNKHARDT BY ATTORNEY Utlit This invention relates to an ignitor for use particularly in liquid propellant rockets.

The pending application of Tinkelenberg, Serial No. 822,687, filed June 24, 1959, describes a pre-ignition chamber in which the propellants are first mixed and ignited at low pressure in conjunction with a communicating ignition chamber in which further and more extensive combustion takes place to produce a substantial torch of combustion products into the main rocket chamber. A feature of the present invention is the control of the flow of one of the propellants to the pre-ignition and ignition chambers as a function of the supply pressure of the propellant.

One feature of the invention is an ignitor of this character having propellant discharge openings in each chamber with a valve for dividing the propellant flow to the chamber in response to varying propellant supply pressure. Another feature is the ignition of the propellants in the pre-ignition chamber and when ignition has begun the transfer of the supply of one of the propellants from the pre-ignition chamber to the ignition chamber so that further combustion will take place in the auxiliary chamber.

Other features and advantages will be apparent from the specification and claims, and from the accompanying drawing which illustrates an embodiment of the invention.

FIG. 1 is a longitudinal sectional view through the ignitor.

FIG. 2 is a sectional view on a larger scale of the valve. Referring first to FIG. 1 the main combustion chamber 2 has an end wall 4 with an opening 6 therein to receive the ignitor assembly 8. The wall 4 includes a sleeve 10 surrounding the ignitor and providing a second opening 12 axially spaced from the opening 6.

The ignitor assembly includes a pre-ignition chamber 14 in the wall 16 of which is positioned a spark plug 18, a nozzle 20 for one of the propellants, for example, the fuel, and another nozzle 22 for the other propellant, for example, the oxidizer. The nozzle 22 is located substantially in axial alignment with the axis of the chamber 14.

The chamber :14 is connected by a throat or passage 24 to the ignition chamber 26, the latter being defined by a sleeve 28 attached at one end to the throat 24 and having the opposite end partially closed by a cap 30. The cap has a central opening 32 for the discharge of combustion products into the main chamber 2. The chambers 14 and 26 are in axial alignment and the passage 24 forms an axial connection between the chambers. The nozzle 22 is substantially in axial alignment with the passage 24 so that as propellant pressures increase, the oxidizer from this nozzle will be discharged through passage 24 into chamber 26.

Surrounding the throat 24 is a ring 34 forming a manifold for one of the propellants, preferably the fuel, and this propellant is discharged through a ring of openings 36 surrounding the throat and arranged in such a way as to direct the fuel into ignition chamber 26. These openings 36 are preferably arranged at an acute angle to the axis of the two chambers so that the fluid discharged through the several openings converges at a point substantially midway of the ignition chamber.

The walls of the ignition chamber may be cooled by the flow of a propellant or other coolant from the space atent O 38 within the wall 4 through coaxial chambers 40 and 42 surrounding the ignition chamber and thence between the cap 30 and a cooperating outer cap 44.

In setting the ignitor in operation propellants are supplied to the nozzle 22 and to an inlet pipe 46 communicating with the nozzle 20. These propellants at this time are supplied at tank pressure which is relatively low but adequate to assure an intermixing of the propellants within the chamber 14 so that they may be ignited by the spark plug 18 to form a pilot flame.

The supply of propellants to the main chamber 2 is controlled by pumps which are set in operation substantially at the time that the supply of propellants to the nozzle 22 and duct 46 is turned on. The pilot or pre-ignition flame in the chamber 14 is started prior to the pressure delivery of propellants to the main fuel chamber so that there will be, when the propellants begin to reach chamber 2, an igniting flame already available.

As the pumps begin to be effective so that the pressure at which the propellants are supplied to the ducts 22 and 46 increases, the supply of propellant (the fuel) is shifted from the nozzle 20 to the manifold 34. This is accomplished by a suitable valve, one example of which is shown in detail in FIG. 2.

In the arrangement shown, the valve casing 48 has a valve 50 slidable therein and this valve is held in the position shown during starting by the compression spring 52 acting on the end of the valve. The valve 50 has a central passage 54 such that when the valve is moved against the force of the spring 52 fluid will flow through the passage 54 through side ports 56 communicating therewith and around the plug end 58 of the valve into a chamber 60. This plug end 58 closely fits the casing and effectively cuts off fluid flow into duct 62 until the valve is moved against the pressure of spring 52 to carry the plug into the chamber 60. From this chamber a conduit 62 connects with the manifold 34. The valve 50 has a head 64 in a position to engage with the port 66 in casing 48 which communicates with the duct 20 there by to close off this duct as pressure increases in the fuel inlet duct 46.

Accordingly, as pressures build up within the propellant systems the unbalanced pressure acting on the valve 50 will move the valve against the compression of the spring 52 closing oil the conduit 20 and admitting fuel past the plug end 58 of the valve and through duct 62 to the manifold 34. Fuel is then delivered into the chamber 26 through the passages 36 and this fuel mixes with the oxidizer from the nozzle 22. The pilot flame within the chamber 14 is carried by the increasing pressure of the oxidizer and fuel into the ignition chamber 26 from which the pressures of the propellants force the combusting propellants in the form of a torch through the opening 32 and into the main combustion chamber.

The particular arrangement for the supply of the propellants under pressure to the main combustion chamher 2 and also to the ignition mechanism. is not a part of the present invention. It is believed suflicient to note that the function of the valve '50 is to divert the fuel delivered to the ignitor from the duct 20 leading to the pre-ignition chamber to the manifold 34 and thence into ignition chamber 26' when increasing pressures on the propellants are high enough so that combustion within the ignition chamber 26 is essential for the purpose of igniting the propellants in the main chamber.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. An ignitor for a main combustion enclosure comprising a pre-ignition chamber and an ignition chamber,

means including a passage supplying a first propellant to said chambers, said pre-ignition chamber being axially aligned and serially connected with said ignition chamber whereby said first propellant will flow through said preignition chamber to said ignition chamber, and a valve responsive to the pressure of a second propellant supplying said second propellant to said pre-ignition chamber responsive to low pressure of said second propellant, said valve responding to increased pressures of said second propellant to supply second propellant to said ignition chamber and simultaneously reduce the supply of said second propellant to said pre-ignition chamber.

2. An ignitor according to claim 1 wherein said valve excludes said second propellant from said ignition chamber at low pressures of said second propellant.

3. An ignitor according to claim 1 wherein said valve excludes said second propellant from said pre-ignition chamber at elevated pressures of said second propellant.

4. An ignitor as in claim 1 in which said valve delivers the flow of said second propellant solely to said pro-ignition chamber at low propellant pressures.

5. An ignitor as in claim 1 in which said passage is dis posed between said chambers and is coaxial therewith and in which the first of said propellants is directed into said pre-ignition chamber substantially in alignment with said passage.

References Cited in the file of this patent 

